Storefront MCP search_shop_catalog no longer accepting null filters

MCP & LLM
1

Hello,

We have been using the Storefront MCP for a while now, specifically the search_shop_catalog tool quite often. Up until now, we’ve had success with it.

Today we noticed that we are getting the following error back when calling this tool:

"error": {
    "code": -32603,
    "data": "Invalid arguments: The property '#/filters' of type null did not match the following type: array in schema e95474c2-1f53-574b-8a3e-404d369ea184, The property '#/country' of type null did not match the following type: string in schema e95474c2-1f53-574b-8a3e-404d369ea184, The property '#/language' of type null did not match the following type: string in schema e95474c2-1f53-574b-8a3e-404d369ea184, The property '#/after' of type null did not match the following type: string in schema e95474c2-1f53-574b-8a3e-404d369ea184",
    "message": "MCP error -32603: Internal error",
    "name": "McpError",
    "stack": "McpError: MCP error -32603: Internal error\n    at Client._onresponse
<omitted for privacy>"
  }

According to the error message, it seems the MCP server is no longer accepting null values for some of the optional tool arguments.

As far as I can tell, we used to be able to pass null values for optional tool arguments.

Is this an intentional change on the Storefront MCP validating tool input schema?

Thank you in advance for any guidance, and let me know if I can provide more details. I’ll reply if I find any more relevant details.

Edit: I confirmed that by stripping out arguments with null value from the tool call, the tool call now succeeds. So it does seem like that is the specific issue.

2

Hi @AustinTildei

I’m investigating if this is a result of a recent change - however this does appear to the functionality now.

3

Hi @AustinTildei

Confirming this was an intentional change related to an update we made to the infrastructure of the MCP. You can continue to use it without arguments that have a null value.

Thanks again for flagging this - and let us know if you have any other questions!

4

Thank you for confirming, @Liam-Shopify .

Is there anywhere I could have subscribed to be aware of this incoming change in advance? I am just thinking about the future and ensuring compatibility proactively instead of retroactively.

Thanks again,

Austin

5

Hi again Austin,

We currently don’t have a changelog for this tool, but the team are exploring options for communicating updates.

6

OK, thank you for following up!